Most skyscrapers don’t do much more than house people or offices, but one day, they could also help solve problems like urban pollution and waste collection. For the last nine years, eVolo Magazine has held a competition for the problem-solving skyscrapers of the future. Here are a handful of this year’s ideas, selected from over 600 entries from around the world. Scroll through the images above for more solutions.

While most of the concepts were designed for cities, a few were made for more remote locations. The Rainforest Guardian, from Chinese architects Jie Huang, Jin Wei, Qiaowan Tang, Yiwei Yu, and Zhe Hao, was made to sit on the edge of the Amazon, capturing and storing rainwater in the rainy season to help fight fires in the dry season. On top, the building could also be used as a lab for scientists studying the area.

The floating Seawer skyscraper, from South Korean architect Sung Jin Cho, is designed to travel through oceans filtering plastic waste out of the water. Housing, offices, and gardens are built into the top of the structure, along with a recycling plant that can process the plastic particles. Everything runs on renewable energy generated from the sun, ocean, and the plastic itself.

In China, where only three out of 74 major cities manages to meet minimums standards for air quality, the Project Blue skyscraper could both remove pollution and create new fuel for cars. Designed by Yang Siqi, Zhan Beidi, Zhao Renbo, and Zhang Tian, the building floats through cities using a chemical reaction with carbon monoxide in the air to create fuel, and then delivers it to underground pipes.

Most of these ideas are far from feasible right now, but they’re exactly the kind of crazy provocations that could eventually spur real change.